Istiṣḥāb is the presumption of the continuity of the previous state. It is an instrument of derivation used in the process of deducing and inferring Islamic Laws.  There are different reasons why experts in legal theories differ in their opinions concerning the application of Istiṣḥāb in the doubts concerning the obligations, better known as shubahāt ḥukmiyya. The most contentious issue which has been debated from the time of Muḥaqiq Narāqī as of today pertains to the relationship between Istiṣḥāb of non-legislation and the Istiṣḥāb of constancy of the legislated. Do these two presumptions of continuity hold good and apply at the same time, or one of them overrides the other. Does the governance (ḥukūma) of one of them not suggest that they are essentially in conflict with each other? Using juristic and inferential methods, descriptive, analytical and critical data processing, library resources, computer systems, scientific software and oral interviews, this research has drawn conclusions some of which are stated as follows:  1. The governance (ḥukūma) of the Istiṣḥāb of non-legislation of a binding law over the Istiṣḥāb of constancy of the legislated and, likewise, the governance of the constancy of the legislated over the Istiṣḥāb of non-legislation are denied due, mainly, to the rationality of the sequence in the causality of the doubt in relation to the other. 2. Imam Khomeni's argument to refute any conflict between the two Istiṣḥāb, which in reality originates in the difference of the subjects, is in order. 3. The negation of conflict between the two Istiṣḥābs on the part of Shahīd Bāqir al-Ṣadr through sorting out the essence of the law into ḥaml shāyiʿ and ḥaml awwalī does not solve the conflict. Thus, the same objection that was leveled against Muḥaqiq al-Khurāsānī's to refute conflict can be directed to him. The subject matter and a thorough study of the reasons and positions and critique of the profound negation of Shahīd al-Ṣadr of the conflict by relying on the reality of legislation and the legislated (jaʿl and majʿūl) are among the innovations of this article.